Solders



Patented May 15, 1951 UNITED STATES ?ATENT OFFICE SOLDERS No Drawing.Application September '7, 1950, Se-

rial No. 183,660. In Great Britain November 2 Claims. (Cl. 75-175) Thisinvention relates to improved solders of the tin/zinc class containing apreponderating proportion of tin, for use particularly in solderingaluminum or aluminum base alloys.

solders of this class have been known for many years and there has beena number of proposals for modifying them by the addition of variousminor constituents such for example as aluminium, bismuth, lead,phosphorus, silver.

One of the major requirements in a solder is good fluidity to enableuniform spreading and complete coverage of the surface to be bonded, andthe object of this invention is to provide an improved solder having inparticular a considerably improved degree of fluidity in comparison withpreviously suggested solders of this class.

According to the present invention we provide a solder of the kinddescribed containing 69.9 to 98.9% tin, 1 to 30% zinc, and 0.1 to 5%cerium.

In addition to the improved fluidity, the cerium also exerts abeneficial effect on the corrosion resistance of the solder. If desiredthe solder may also contain (ll-5% of aluminium for the purpose offurther increasing its corrosion resistance. The cerium content mayconveniently be added in the form of misch metal. In the accompanyingtable there are given comparative corrosion and fluidity data for aseries of alloys in accordance with the present invention and thecorresponding basic alloys not containing cerium. The corrosion resultsare expressed in terms of the time to failure, in hours, of soldered lapjoints of aluminium in a salt spray cabinet, and

the fluidity readings are represented by the spread of a standard 1 gramsample of solder on a fluxed sheet of aluminium held at the statedtemperature.

Table Fluidity (spread of oomposltwn Per Cent Time to faildrop in mm.)at?- ure of lap joint in hours Sn Z11 Al Ce 300 0. 350 0. 400 C.

95 5 450 13 36 94. 5 5 550 26 44 78 90 10 200 14 36 48 89. 5 10 400 2845 81 88 10 500 30 52 90 80 20 l, 050 13 31 42 79. 5 20 1, 300 27 42 7578 20 1, 400 31 84 25 -l l, 400 25 36 74. 5 25 0. 5 1,550 36 52 88 10 2650 18 36 47 87. 5 l0 2 0. 5 750 25 39 67 86 10 2 2 850 29 50 78 78 20 21, 650 17 34 45 77. 6 20 2 0 5 1, 800 27 46 68 76 20 2 2 l, 950 54 80 Weclaim:

1. Solder containing 69.9-98.9% tin, 1-30% zinc, and 0.1-5% cerium.

2. Solder in accordance with claim 1, containing in addition 0.1-5%aluminium.

RICHARD CI-IADWICK. WILLIAM G. I-IEATON.

No references cited.

1. SOLDER CONTAINING 69.9-98.9% TIN, 1-30% ZINC, AND 0.1-5% CERIUM.